In recent years, TCP/IP (Transmission Control Protocol/Internet Protocol) has been widely used as a protocol for performing communication among multiple hosts. The process for TCP/IP is performed at the time of reception and at the time of transmission, in accordance with the specification of the protocol, and this process is generally performed by software that operates on a CPU (Central Processing Unit). However, in association with the broadness of network bandwidths in recent years, it has been proposed that the protocol process for TCP/IP be performed by dedicated hardware.